/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/*  $OpenBSD: queue.h,v 1.32 2007/04/30 18:42:34 pedro Exp $  */
/*  $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */

/*
 * Copyright (c) 1991, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  @(#)queue.h 8.5 (Berkeley) 8/20/94
 */

#ifndef _SYS_QUEUE_H_
#define _SYS_QUEUE_H_

/*
 * This file defines five types of data structures: singly-linked lists,
 * lists, simple queues, tail queues, and circular queues.
 *
 *
 * A singly-linked list is headed by a single forward pointer. The elements
 * are singly linked for minimum space and pointer manipulation overhead at
 * the expense of O(n) removal for arbitrary elements. New elements can be
 * added to the list after an existing element or at the head of the list.
 * Elements being removed from the head of the list should use the explicit
 * macro for this purpose for optimum efficiency. A singly-linked list may
 * only be traversed in the forward direction.  Singly-linked lists are ideal
 * for applications with large datasets and few or no removals or for
 * implementing a LIFO queue.
 *
 * A list is headed by a single forward pointer (or an array of forward
 * pointers for a hash table header). The elements are doubly linked
 * so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before
 * or after an existing element or at the head of the list. A list
 * may only be traversed in the forward direction.
 *
 * A simple queue is headed by a pair of pointers, one the head of the
 * list and the other to the tail of the list. The elements are singly
 * linked to save space, so elements can only be removed from the
 * head of the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the
 * list. A simple queue may only be traversed in the forward direction.
 *
 * A tail queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or
 * after an existing element, at the head of the list, or at the end of
 * the list. A tail queue may be traversed in either direction.
 *
 * A circle queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the list.
 * A circle queue may be traversed in either direction, but has a more
 * complex end of list detection.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 */

#if defined(QUEUE_MACRO_DEBUG) || (defined(_KERNEL) && defined(DIAGNOSTIC))
#define _Q_INVALIDATE(a) (a) = ((void *)-1)
#else
#define _Q_INVALIDATE(a)
#endif

/*
 * Singly-linked List definitions.
 */
#define SLIST_HEAD(name, type)            \
struct name {               \
	struct type *slh_first; /* first element */     \
}

#define SLIST_HEAD_INITIALIZER(head)          \
	{ NULL }

#define SLIST_ENTRY(type)           \
struct {                \
	struct type *sle_next;  /* next element */      \
}

/*
 * Singly-linked List access methods.
 */
#define SLIST_FIRST(head) ((head)->slh_first)
#define SLIST_END(head)   NULL
#define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
#define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)

#define SLIST_FOREACH(var, head, field)         \
	for ((var) = SLIST_FIRST(head);          \
		 (var) != SLIST_END(head);         \
		 (var) = SLIST_NEXT(var, field))

#define SLIST_FOREACH_PREVPTR(var, varp, head, field)     \
	for ((varp) = &SLIST_FIRST((head));       \
		 ((var) = *(varp)) != SLIST_END(head);     \
		 (varp) = &SLIST_NEXT((var), field))

/*
 * Singly-linked List functions.
 */
#define SLIST_INIT(head) do {            \
	SLIST_FIRST(head) = SLIST_END(head);        \
} while (0)

#define SLIST_INSERT_AFTER(slistelm, elm, field) do {     \
	(elm)->field.sle_next = (slistelm)->field.sle_next;   \
	(slistelm)->field.sle_next = (elm);       \
} while (0)

#define SLIST_INSERT_HEAD(head, elm, field) do {      \
	(elm)->field.sle_next = (head)->slh_first;      \
	(head)->slh_first = (elm);          \
} while (0)

#define SLIST_REMOVE_NEXT(head, elm, field) do {      \
	(elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;  \
} while (0)

#define SLIST_REMOVE_HEAD(head, field) do {       \
	(head)->slh_first = (head)->slh_first->field.sle_next;    \
} while (0)

#define SLIST_REMOVE(head, elm, type, field) do {     \
	if ((head)->slh_first == (elm)) {       \
		SLIST_REMOVE_HEAD((head), field);     \
	} else {              \
		struct type *curelm = (head)->slh_first;    \
		while (curelm->field.sle_next != (elm))     \
			curelm = curelm->field.sle_next;    \
		curelm->field.sle_next =        \
			curelm->field.sle_next->field.sle_next;   \
		_Q_INVALIDATE((elm)->field.sle_next);     \
	}               \
} while (0)

/*
 * List definitions.
 */
#define LIST_HEAD(name, type)           \
struct name {               \
	struct type *lh_first;  /* first element */     \
}

#define LIST_HEAD_INITIALIZER(head)         \
	{ NULL }

#define LIST_ENTRY(type)            \
struct {                \
	struct type *le_next; /* next element */      \
	struct type **le_prev;  /* address of previous next element */  \
}

/*
 * List access methods
 */
#define LIST_FIRST(head)    ((head)->lh_first)
#define LIST_END(head)      NULL
#define LIST_EMPTY(head)    (LIST_FIRST(head) == LIST_END(head))
#define LIST_NEXT(elm, field)   ((elm)->field.le_next)

#define LIST_FOREACH(var, head, field)          \
	for ((var)  = LIST_FIRST(head);         \
		 (var) != LIST_END(head);         \
		 (var)  = LIST_NEXT(var, field))

/*
 * List functions.
 */
#define LIST_INIT(head) do {            \
	LIST_FIRST(head) = LIST_END(head);        \
} while (0)

#define LIST_INSERT_AFTER(listelm, elm, field) do {     \
	if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
		(listelm)->field.le_next->field.le_prev =   \
			&(elm)->field.le_next;        \
	(listelm)->field.le_next = (elm);       \
	(elm)->field.le_prev = &(listelm)->field.le_next;   \
} while (0)

#define LIST_INSERT_BEFORE(listelm, elm, field) do {      \
	(elm)->field.le_prev = (listelm)->field.le_prev;    \
	(elm)->field.le_next = (listelm);       \
	*(listelm)->field.le_prev = (elm);        \
	(listelm)->field.le_prev = &(elm)->field.le_next;   \
} while (0)

#define LIST_INSERT_HEAD(head, elm, field) do {       \
	if (((elm)->field.le_next = (head)->lh_first) != NULL)    \
		(head)->lh_first->field.le_prev = &(elm)->field.le_next;\
	(head)->lh_first = (elm);         \
	(elm)->field.le_prev = &(head)->lh_first;     \
} while (0)

#define LIST_REMOVE(elm, field) do {          \
	if ((elm)->field.le_next != NULL)       \
		(elm)->field.le_next->field.le_prev =     \
			(elm)->field.le_prev;       \
	*(elm)->field.le_prev = (elm)->field.le_next;     \
	_Q_INVALIDATE((elm)->field.le_prev);        \
	_Q_INVALIDATE((elm)->field.le_next);        \
} while (0)

#define LIST_REPLACE(elm, elm2, field) do {       \
	if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
		(elm2)->field.le_next->field.le_prev =      \
			&(elm2)->field.le_next;       \
	(elm2)->field.le_prev = (elm)->field.le_prev;     \
	*(elm2)->field.le_prev = (elm2);        \
	_Q_INVALIDATE((elm)->field.le_prev);        \
	_Q_INVALIDATE((elm)->field.le_next);        \
} while (0)

/*
 * Simple queue definitions.
 */
#define SIMPLEQ_HEAD(name, type)          \
struct name {               \
	struct type *sqh_first; /* first element */     \
	struct type **sqh_last; /* addr of last next element */   \
}

#define SIMPLEQ_HEAD_INITIALIZER(head)          \
	{ NULL, &(head).sqh_first }

#define SIMPLEQ_ENTRY(type)           \
struct {                \
	struct type *sqe_next;  /* next element */      \
}

/*
 * Simple queue access methods.
 */
#define SIMPLEQ_FIRST(head)     ((head)->sqh_first)
#define SIMPLEQ_END(head)     NULL
#define SIMPLEQ_EMPTY(head)     (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
#define SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)

#define SIMPLEQ_FOREACH(var, head, field)       \
	for ((var) = SIMPLEQ_FIRST(head);        \
		 (var) != SIMPLEQ_END(head);         \
		 (var) = SIMPLEQ_NEXT(var, field))

/*
 * Simple queue functions.
 */
#define SIMPLEQ_INIT(head) do {           \
	(head)->sqh_first = NULL;         \
	(head)->sqh_last = &(head)->sqh_first;        \
} while (0)

#define SIMPLEQ_INSERT_HEAD(head, elm, field) do {      \
	if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)  \
		(head)->sqh_last = &(elm)->field.sqe_next;    \
	(head)->sqh_first = (elm);          \
} while (0)

#define SIMPLEQ_INSERT_TAIL(head, elm, field) do {      \
	(elm)->field.sqe_next = NULL;         \
	*(head)->sqh_last = (elm);          \
	(head)->sqh_last = &(elm)->field.sqe_next;      \
} while (0)

#define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {    \
	if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
		(head)->sqh_last = &(elm)->field.sqe_next;    \
	(listelm)->field.sqe_next = (elm);        \
} while (0)

#define SIMPLEQ_REMOVE_HEAD(head, field) do {     \
	if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
		(head)->sqh_last = &(head)->sqh_first;      \
} while (0)

/*
 * Tail queue definitions.
 */
#define TAILQ_HEAD(name, type)            \
struct name {               \
	struct type *tqh_first; /* first element */     \
	struct type **tqh_last; /* addr of last next element */   \
}

#define TAILQ_HEAD_INITIALIZER(head)          \
	{ NULL, &(head).tqh_first }

#define TAILQ_ENTRY(type)           \
struct {                \
	struct type *tqe_next;  /* next element */      \
	struct type **tqe_prev; /* address of previous next element */  \
}

/*
 * tail queue access methods
 */
#define TAILQ_FIRST(head)   ((head)->tqh_first)
#define TAILQ_END(head)     NULL
#define TAILQ_NEXT(elm, field)    ((elm)->field.tqe_next)
#define TAILQ_LAST(head, headname)          \
	(*(((struct headname *)((head)->tqh_last))->tqh_last))
/* XXX */
#define TAILQ_PREV(elm, headname, field)        \
	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
#define TAILQ_EMPTY(head)           \
	(TAILQ_FIRST(head) == TAILQ_END(head))

#define TAILQ_FOREACH(var, head, field)         \
	for ((var) = TAILQ_FIRST(head);          \
		 (var) != TAILQ_END(head);         \
		 (var) = TAILQ_NEXT(var, field))

#define TAILQ_FOREACH_REVERSE(var, head, headname, field)   \
	for ((var) = TAILQ_LAST(head, headname);       \
		 (var) != TAILQ_END(head);         \
		 (var) = TAILQ_PREV(var, headname, field))

/*
 * Tail queue functions.
 */
#define TAILQ_INIT(head) do {           \
	(head)->tqh_first = NULL;         \
	(head)->tqh_last = &(head)->tqh_first;        \
} while (0)

#define TAILQ_INSERT_HEAD(head, elm, field) do {      \
	if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)  \
		(head)->tqh_first->field.tqe_prev =     \
			&(elm)->field.tqe_next;       \
	else                \
		(head)->tqh_last = &(elm)->field.tqe_next;    \
	(head)->tqh_first = (elm);          \
	(elm)->field.tqe_prev = &(head)->tqh_first;     \
} while (0)

#define TAILQ_INSERT_TAIL(head, elm, field) do {      \
	(elm)->field.tqe_next = NULL;         \
	(elm)->field.tqe_prev = (head)->tqh_last;     \
	*(head)->tqh_last = (elm);          \
	(head)->tqh_last = &(elm)->field.tqe_next;      \
} while (0)

#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {    \
	if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
		(elm)->field.tqe_next->field.tqe_prev =     \
			&(elm)->field.tqe_next;       \
	else                \
		(head)->tqh_last = &(elm)->field.tqe_next;    \
	(listelm)->field.tqe_next = (elm);        \
	(elm)->field.tqe_prev = &(listelm)->field.tqe_next;   \
} while (0)

#define TAILQ_INSERT_BEFORE(listelm, elm, field) do {     \
	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;    \
	(elm)->field.tqe_next = (listelm);        \
	*(listelm)->field.tqe_prev = (elm);       \
	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;   \
} while (0)

#define TAILQ_REMOVE(head, elm, field) do {       \
	if (((elm)->field.tqe_next) != NULL)        \
		(elm)->field.tqe_next->field.tqe_prev =     \
			(elm)->field.tqe_prev;        \
	else                \
		(head)->tqh_last = (elm)->field.tqe_prev;   \
	*(elm)->field.tqe_prev = (elm)->field.tqe_next;     \
	_Q_INVALIDATE((elm)->field.tqe_prev);       \
	_Q_INVALIDATE((elm)->field.tqe_next);       \
} while (0)

#define TAILQ_REPLACE(head, elm, elm2, field) do {      \
	if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
		(elm2)->field.tqe_next->field.tqe_prev =    \
			&(elm2)->field.tqe_next;        \
	else                \
		(head)->tqh_last = &(elm2)->field.tqe_next;   \
	(elm2)->field.tqe_prev = (elm)->field.tqe_prev;     \
	*(elm2)->field.tqe_prev = (elm2);       \
	_Q_INVALIDATE((elm)->field.tqe_prev);       \
	_Q_INVALIDATE((elm)->field.tqe_next);       \
} while (0)

/*
 * Circular queue definitions.
 */
#define CIRCLEQ_HEAD(name, type)          \
struct name {               \
	struct type *cqh_first;   /* first element */   \
	struct type *cqh_last;    /* last element */    \
}

#define CIRCLEQ_HEAD_INITIALIZER(head) do {         \
	CIRCLEQ_END(&head), CIRCLEQ_END(&head)          \
} while (0)

#define CIRCLEQ_ENTRY(type)           \
struct {                \
	struct type *cqe_next;    /* next element */    \
	struct type *cqe_prev;    /* previous element */    \
}

/*
 * Circular queue access methods
 */
#define CIRCLEQ_FIRST(head)   ((head)->cqh_first)
#define CIRCLEQ_LAST(head)    ((head)->cqh_last)
#define CIRCLEQ_END(head)   ((void *)(head))
#define CIRCLEQ_NEXT(elm, field)  ((elm)->field.cqe_next)
#define CIRCLEQ_PREV(elm, field)  ((elm)->field.cqe_prev)
#define CIRCLEQ_EMPTY(head)           \
	(CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))

#define CIRCLEQ_FOREACH(var, head, field)       \
	for ((var) = CIRCLEQ_FIRST(head);        \
		 (var) != CIRCLEQ_END(head);         \
		 (var) = CIRCLEQ_NEXT(var, field))

#define CIRCLEQ_FOREACH_REVERSE(var, head, field)     \
	for ((var) = CIRCLEQ_LAST(head);         \
		 (var) != CIRCLEQ_END(head);         \
		 (var) = CIRCLEQ_PREV(var, field))

/*
 * Circular queue functions.
 */
#define CIRCLEQ_INIT(head) do {           \
	(head)->cqh_first = CIRCLEQ_END(head);        \
	(head)->cqh_last = CIRCLEQ_END(head);       \
} while (0)

#define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {    \
	(elm)->field.cqe_next = (listelm)->field.cqe_next;    \
	(elm)->field.cqe_prev = (listelm);        \
	if ((listelm)->field.cqe_next == CIRCLEQ_END(head))   \
		(head)->cqh_last = (elm);       \
	else                \
		(listelm)->field.cqe_next->field.cqe_prev = (elm);  \
	(listelm)->field.cqe_next = (elm);        \
} while (0)

#define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {   \
	(elm)->field.cqe_next = (listelm);        \
	(elm)->field.cqe_prev = (listelm)->field.cqe_prev;    \
	if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))   \
		(head)->cqh_first = (elm);        \
	else                \
		(listelm)->field.cqe_prev->field.cqe_next = (elm);  \
	(listelm)->field.cqe_prev = (elm);        \
} while (0)

#define CIRCLEQ_INSERT_HEAD(head, elm, field) do {      \
	(elm)->field.cqe_next = (head)->cqh_first;      \
	(elm)->field.cqe_prev = CIRCLEQ_END(head);      \
	if ((head)->cqh_last == CIRCLEQ_END(head))      \
		(head)->cqh_last = (elm);       \
	else                \
		(head)->cqh_first->field.cqe_prev = (elm);    \
	(head)->cqh_first = (elm);          \
} while (0)

#define CIRCLEQ_INSERT_TAIL(head, elm, field) do {      \
	(elm)->field.cqe_next = CIRCLEQ_END(head);      \
	(elm)->field.cqe_prev = (head)->cqh_last;     \
	if ((head)->cqh_first == CIRCLEQ_END(head))     \
		(head)->cqh_first = (elm);        \
	else                \
		(head)->cqh_last->field.cqe_next = (elm);   \
	(head)->cqh_last = (elm);         \
} while (0)

#define CIRCLEQ_REMOVE(head, elm, field) do {       \
	if ((elm)->field.cqe_next == CIRCLEQ_END(head))     \
		(head)->cqh_last = (elm)->field.cqe_prev;   \
	else                \
		(elm)->field.cqe_next->field.cqe_prev =     \
			(elm)->field.cqe_prev;        \
	if ((elm)->field.cqe_prev == CIRCLEQ_END(head))     \
		(head)->cqh_first = (elm)->field.cqe_next;    \
	else                \
		(elm)->field.cqe_prev->field.cqe_next =     \
			(elm)->field.cqe_next;        \
	_Q_INVALIDATE((elm)->field.cqe_prev);       \
	_Q_INVALIDATE((elm)->field.cqe_next);       \
} while (0)

#define CIRCLEQ_REPLACE(head, elm, elm2, field) do {      \
	if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==   \
		CIRCLEQ_END(head))            \
		(head).cqh_last = (elm2);       \
	else                \
		(elm2)->field.cqe_next->field.cqe_prev = (elm2);  \
	if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==   \
		CIRCLEQ_END(head))            \
		(head).cqh_first = (elm2);        \
	else                \
		(elm2)->field.cqe_prev->field.cqe_next = (elm2);  \
	_Q_INVALIDATE((elm)->field.cqe_prev);       \
	_Q_INVALIDATE((elm)->field.cqe_next);       \
} while (0)

#endif							/* !_SYS_QUEUE_H_ */
